62 



PEOF. E. W. CLAYPOLE ON PIERASPIDIAlSr EISH IN 



without intervening spaces ; furrows between ridges consequently 

 angular. Diameter at base about one eighth of an inch. 



Horizon and locality. Clinton group, Iron-sandstone, Perry co.; 

 Pennsylvania. 



Pal^aspis, g. n. 

 The genus has been sufficiently described in the body of the paper. 

 Pig. 7. — Outline of Shield o/Palseaspis americana. (isTat. size.) 



The striation is shown only over a part of the. shield, but extends really 

 over all. 



Pal^aspis ameeicana, sp. n. (Fig. 7.) 



Shield elliptical in outline, truncate at one end, convex on upper 

 surface, between two and three inches long ; lateral edges rolling in 

 under the upper surface ; thickness not exceeding ^ inch over its 

 whole extent. Upper surface covered with a tracery consisting of 

 fine, delicate, flowing, depressed lines branching and anastomosing, 

 but in general keeping directions rudely parallel, often abruptly 

 curving near the end from both sides towards the medial line, where 

 they terminate without ending in a spine. 



Locality and horizon. Perry county, Pennsylvania, in the Bloom- 

 field Sandstone or uppermost member of the Onondaga Yariegated 

 Shales. 



Pal^aspis biteiincata, sp. n. (Fig. 8.) 



Shield elliptical, truncate at hoth ends, more convex than P. ame- 



